Eugenics (/juːˈdʒɛnɪks/; from Greek εὐγενής eugenes "well-born" from εὖ eu, "good, well" and γένος genos, "race, stock, kin")[2][3] is a set of beliefs and practices that aims at improving the genetic quality of the human population.[4][5] The exact definition of eugenics has been a matter of debate since the term was coined.

Frederick Osborn's 1937 journal article "Development of a Eugenic Philosophy"[6] framed it as a social philosophy—that is, a philosophy with implications for social order. That definition is not universally accepted. Osborn advocated for higher rates of sexual reproduction among people with desired traits (positive eugenics), or reduced rates of sexual reproduction and sterilization of people with less-desired or undesired traits (negative eugenics).

Alternatively, gene selection rather than "people selection" has recently been made possible through advances in genome editing.[7]

While eugenic principles have been practiced as far back in world history as ancient Greece, the modern history of eugenics began in the early 20th century when a popular eugenics movement emerged in the United Kingdom[8] and spread to many countries, including the United States, Canada[9] and most European countries. In this period, eugenic ideas were espoused across the political spectrum. Consequently, many countries adopted eugenic policies meant to improve the genetic stock of their countries. Such programs often included both "positive" measures, such as encouraging individuals deemed particularly "fit" to reproduce, and "negative" measures such as marriage prohibitions and forced sterilization of people deemed unfit for reproduction. People deemed unfit to reproduce often included people with mental or physical disabilities, people who scored in the low ranges of different IQ tests, criminals and deviants, and members of disfavored minority groups. The eugenics movement became negatively associated with Nazi Germany and the Holocaust when many of the defendants at the Nuremberg trials attempted to justify their human rights abuses by claiming there was little difference between the Nazi eugenics programs and the US eugenics programs.[10] In the decades following World War II, with the institution of human rights, many countries gradually abandoned eugenics policies, although some Western countries, among them the United States, continued to carry out forced sterilizations.

A major criticism of eugenics policies is that, regardless of whether "negative" or "positive" policies are used, they are vulnerable to abuse because the criteria of selection are determined by whichever group is in political power. Furthermore, negative eugenics in particular is considered by many to be a violation of basic human rights, which include the right to reproduction. Another criticism is that eugenic policies eventually lead to a loss of genetic diversity, resulting in inbreeding depression instead due to a low genetic variation.

The concept of positive eugenics to produce better human beings has existed at least since Plato suggested selective mating to produce a guardian class.[12] The idea of negative eugenics to decrease the birth of inferior human beings has existed at least since William Goodell (1829-1894) advocated the castration and spaying of the insane.[13][14]

The idea of a modern project of improving the human population through a statistical understanding of heredity used to encourage good breeding was originally developed by Francis Galton and, initially, was closely linked to Darwinism and the theory of natural selection.[15] Galton had read his half-cousin Charles Darwin's theory of evolution, which sought to explain the development of plant and animal species, and desired to apply it to humans. Based on his biographical studies, Galton believed that desirable human qualities were hereditary traits, though Darwin strongly disagreed with this elaboration of his theory.[16] In 1883, one year after Darwin's death, Galton gave his research a name: eugenics.[17] With the introduction of genetics, eugenics relied on an ideology of genetic determinism in which human character was due to genes, unaffected by education or living conditions. Many of the early geneticists were not Darwinians, and evolution theory was not needed for eugenics policies based on genetic determinism.[15] Throughout its recent history, eugenics has remained controversial.[18]

Among institutions, the Catholic Church was an opponent of state-enforced sterilizations.[39] Attempts by the Eugenics Education Society to persuade the British government to legalise voluntary sterilisation were opposed by Catholics and by the Labour Party.[page needed] The American Eugenics Society initially gained some Catholic supporters, but Catholic support declined following the 1930 papal encyclical Casti connubii.[20] In this, Pope Pius XI explicitly condemned sterilization laws: "Public magistrates have no direct power over the bodies of their subjects; therefore, where no crime has taken place and there is no cause present for grave punishment, they can never directly harm, or tamper with the integrity of the body, either for the reasons of eugenics or for any other reason."[40]

A Lebensborn birth house in Nazi Germany. Created with intention of raising the birth rate of "Aryan" children from extramarital relations of "racially pure and healthy" parents.

The scientific reputation of eugenics started to decline in the 1930s, a time when Ernst Rüdin used eugenics as a justification for the racial policies of Nazi Germany. Adolf Hitler had praised and incorporated eugenic ideas in Mein Kampf in 1925 and emulated eugenic legislation for the sterilization of "defectives" that had been pioneered in the United States once he took power.[42] Some common early 20th century eugenics methods involved identifying and classifying individuals and their families, including the poor, mentally ill, blind, deaf, developmentally disabled, promiscuous women, homosexuals, and racial groups (such as the Roma and Jews in Nazi Germany) as "degenerate" or "unfit", leading to their segregation or institutionalization, sterilization, euthanasia, and even their mass murder.[43] The Nazi practice of euthanasia was carried out on hospital patients in the Aktion T4 centers such as Hartheim Castle.

By the end of World War II, many discriminatory eugenics laws were abandoned, having become associated with Nazi Germany.[43][44] H. G. Wells, who had called for "the sterilization of failures" in 1904,[45] stated in his 1940 book The Rights of Man: Or What are we fighting for? that among the human rights he believed should be available to all people was "a prohibition on mutilation, sterilization, torture, and any bodily punishment".[46] After World War II, the practice of "imposing measures intended to prevent births within [a population] group" fell within the definition of the new international crime of genocide, set out in the Convention on the Prevention and Punishment of the Crime of Genocide.[47] The Charter of Fundamental Rights of the European Union also proclaims "the prohibition of eugenic practices, in particular those aiming at selection of persons".[48] In spite of the decline in discriminatory eugenics laws, some government mandated sterilization continued into the 21st century. During the ten years President Alberto Fujimori led Peru from 1990 to 2000, allegedly 2,000 persons were involuntarily sterilized.[49] China maintained its coercive one-child policy until 2015 as well as a suite of other eugenics based legislation to reduce population size and manage fertility rates of different populations.[50][51][52] In 2007 the United Nations reported coercive sterilisations and hysterectomies in Uzbekistan.[53] During the years 2005–06 to 2012–13, nearly one-third of the 144 California prison inmates who were sterilized did not give lawful consent to the operation.[54]

Developments in genetic, genomic, and reproductive technologies at the end of the 20th century are raising numerous questions regarding the ethical status of eugenics, effectively creating a resurgence of interest in the subject. Some, such as UC Berkeley sociologist Troy Duster, claim that modern genetics is a back door to eugenics.[55] This view is shared by White House Assistant Director for Forensic Sciences, Tania Simoncelli, who stated in a 2003 publication by the Population and Development Program at Hampshire College that advances in pre-implantation genetic diagnosis (PGD) are moving society to a "new era of eugenics", and that, unlike the Nazi eugenics, modern eugenics is consumer driven and market based, "where children are increasingly regarded as made-to-order consumer products".[56] In a 2006 newspaper article, Richard Dawkins said that discussion regarding eugenics was inhibited by the shadow of Nazi misuse, to the extent that some scientists would not admit that breeding humans for certain abilities is at all possible. He believes that it is not physically different from breeding domestic animals for traits such as speed or herding skill. Dawkins felt that enough time had elapsed to at least ask just what the ethical differences were between breeding for ability versus training athletes or forcing children to take music lessons, though he could think of persuasive reasons to draw the distinction.[57]

Transhumanism is often associated with eugenics, although most transhumanists holding similar views nonetheless distance themselves from the term "eugenics" (preferring "germinal choice" or "reprogenetics")[59] to avoid having their position confused with the discredited theories and practices of early-20th-century eugenic movements.

The origins of the concept began with certain interpretations of Mendelian inheritance, and the theories of August Weismann.[63] The word eugenics is derived from the Greek word eu ("good" or "well") and the suffix -genēs ("born"), and was coined by Galton in 1883 to replace the word "stirpiculture", which he had used previously but which had come to be mocked due to its perceived sexual overtones.[64] Galton defined eugenics as "the study of all agencies under human control which can improve or impair the racial quality of future generations".[65] Galton did not understand the mechanism of inheritance.[66]

Edwin Black, journalist and author of War Against the Weak, claims eugenics is often deemed a pseudoscience because what is defined as a genetic improvement of a desired trait is often deemed a cultural choice rather than a matter that can be determined through objective scientific inquiry.[69] The most disputed aspect of eugenics has been the definition of "improvement" of the human gene pool, such as what is a beneficial characteristic and what is a defect. This aspect of eugenics has historically been tainted with scientific racism.

Eugenics also had a place in medicine. In his lecture "Darwinism, Medical Progress and Eugenics", Karl Pearson said that everything concerning eugenics fell into the field of medicine. He basically placed the two words as equivalents. He was supported in part by the fact that Francis Galton, the father of eugenics, also had medical training.[70]

Eugenic policies have been conceptually divided into two categories. Positive eugenics is aimed at encouraging reproduction among the genetically advantaged; for example, the reproduction of the intelligent, the healthy, and the successful. Possible approaches include financial and political stimuli, targeted demographic analyses, in vitro fertilization, egg transplants, and cloning.[71] The movie Gattaca provides a fictional example of positive eugenics done voluntarily. Negative eugenics aimed to eliminate, through sterilization or segregation, those deemed physically, mentally, or morally "undesirable". This includes abortions, sterilization, and other methods of family planning.[71] Both positive and negative eugenics can be coercive; abortion for fit women, for example, was illegal in Nazi Germany.[72]

Jon Entine claims that eugenics simply means "good genes" and using it as synonym for genocide is an "all-too-common distortion of the social history of genetics policy in the United States." According to Entine, eugenics developed out of the Progressive Era and not "Hitler's twisted Final Solution".[73]

The first major challenge to conventional eugenics based upon genetic inheritance was made in 1915 by Thomas Hunt Morgan, who demonstrated the event of genetic mutation occurring outside of inheritance involving the discovery of the hatching of a fruit fly (Drosophila melanogaster) with white eyes from a family of red-eyes.[109] Morgan claimed that this demonstrated that major genetic changes occurred outside of inheritance and that the concept of eugenics based upon genetic inheritance was not completely scientifically accurate.[109] Additionally, Morgan criticized the view that subjective traits, such as intelligence and criminality, were caused by heredity because he believed that the definitions of these traits varied and that accurate work in genetics could only be done when the traits being studied were accurately defined.[110] In spite of Morgan's public rejection of eugenics, much of his genetic research was absorbed by eugenics.[111][112]

The heterozygotetest is used for the early detection of recessive hereditary diseases, allowing for couples to determine if they are at risk of passing genetic defects to a future child.[113] The goal of the test is to estimate the likelihood of passing the hereditary disease to future descendants.[113]

Recessive traits can be severely reduced, but never eliminated unless the complete genetic makeup of all members of the pool was known, as aforementioned. As only very few undesirable traits, such as Huntington's disease, are dominant, it could be argued[by whom?] from certain perspectives that the practicality of "eliminating" traits is quite low.[citation needed]

There are examples of eugenic acts that managed to lower the prevalence of recessive diseases, although not influencing the prevalence of heterozygote carriers of those diseases. The elevated prevalence of certain genetically transmitted diseases among the Ashkenazi Jewish population (Tay–Sachs, cystic fibrosis, Canavan's disease, and Gaucher's disease), has been decreased in current populations by the application of genetic screening.[114]

Pleiotropy occurs when one gene influences multiple, seemingly unrelated phenotypic traits, an example being phenylketonuria, which is a human disease that affects multiple systems but is caused by one gene defect.[115] Andrzej Pękalski, from the University of Wrocław, argues that eugenics can cause harmful loss of genetic diversity if a eugenics program selects for a pleiotropic gene that is also associated with a positive trait. Pekalski uses the example of a coercive government eugenics program that prohibits people with myopia from breeding but has the unintended consequence of also selecting against high intelligence since the two go together.[116]

Eugenic policies could also lead to loss of genetic diversity, in which case a culturally accepted "improvement" of the gene pool could very likely—as evidenced in numerous instances in isolated island populations (e.g., the dodo, Raphus cucullatus, of Mauritius)—result in extinction due to increased vulnerability to disease, reduced ability to adapt to environmental change, and other factors both known and unknown. A long-term species-wide eugenics plan might lead to a scenario similar to this because the elimination of traits deemed undesirable would reduce genetic diversity by definition.[117]

Edward M. Miller claims that, in any one generation, any realistic program should make only minor changes in a fraction of the gene pool, giving plenty of time to reverse direction if unintended consequences emerge, reducing the likelihood of the elimination of desirable genes.[118] Miller also argues that any appreciable reduction in diversity is so far in the future that little concern is needed for now.[118]

While the science of genetics has increasingly provided means by which certain characteristics and conditions can be identified and understood, given the complexity of human genetics, culture, and psychology there is at this point no agreed objective means of determining which traits might be ultimately desirable or undesirable. Some diseases such as sickle-cell disease and cystic fibrosis respectively confer immunity to malaria and resistance to cholera when a single copy of the recessive allele is contained within the genotype of the individual. Reducing the instance of sickle-cell disease genes in Africa where malaria is a common and deadly disease could indeed have extremely negative net consequences.

However, some genetic diseases such as haemochromatosis can increase susceptibility to illness, cause physical deformities, and other dysfunctions, which provides some incentive for people to re-consider some elements of eugenics.

Autistic people have advocated a shift in perception of autism spectrum disorders as complex syndromes rather than diseases that must be cured. Proponents of this view reject the notion that there is an "ideal" brain configuration and that any deviation from the norm is pathological; they promote tolerance for what they call neurodiversity.[119] Baron-Cohen argues that the genes for Asperger's combination of abilities have operated throughout recent human evolution and have made remarkable contributions to human history.[120] The possible reduction of autism rates through selection against the genetic predisposition to autism is a significant political issue in the autism rights movement, which claims that autism is a part of neurodiversity.

Many culturally Deaf people oppose attempts to cure deafness, believing instead deafness should be considered a defining cultural characteristic not a disease.[121][122][123] Some people have started advocating the idea that deafness brings about certain advantages, often termed "Deaf Gain."[124][125]

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Societal and political consequences of eugenics call for a place in the discussion on the ethics behind the eugenics movement.[126] Many of the ethical concerns regarding eugenics arise from its controversial past, prompting a discussion on what place, if any, it should have in the future. Advances in science have changed eugenics. In the past, eugenics had more to do with sterilization and enforced reproduction laws.[127] Now, in the age of a progressively mapped genome, embryos can be tested for susceptibility to disease, gender, and genetic defects, and alternative methods of reproduction such as in vitro fertilization are becoming more common.[128] Therefore, eugenics is no longer ex post facto regulation of the living but instead preemptive action on the unborn.[129]

With this change, however, there are ethical concerns which lack adequate attention, and which must be addressed before eugenic policies can be properly implemented in the future. Sterilized individuals, for example, could volunteer for the procedure, albeit under incentive or duress, or at least voice their opinion. The unborn fetus on which these new eugenic procedures are performed cannot speak out, as the fetus lacks the voice to consent or to express his or her opinion.[130] Philosophers disagree about the proper framework for reasoning about such actions, which change the very identity and existence of future persons.[131]

In his 2003 book Enough: Staying Human in an Engineered Age, environmental ethicistBill McKibben argued at length against germinal choice technology and other advanced biotechnological strategies for human enhancement. He claims that it would be morally wrong for humans to tamper with fundamental aspects of themselves (or their children) in an attempt to overcome universal human limitations, such as vulnerability to aging, maximum life span and biological constraints on physical and cognitive ability. Attempts to "improve" themselves through such manipulation would remove limitations that provide a necessary context for the experience of meaningful human choice. He claims that human lives would no longer seem meaningful in a world where such limitations could be overcome technologically. Even the goal of using germinal choice technology for clearly therapeutic purposes should be relinquished, since it would inevitably produce temptations to tamper with such things as cognitive capacities. He argues that it is possible for societies to benefit from renouncing particular technologies, using as examples Ming China, Tokugawa Japan and the contemporary Amish.[136]

Some, such as Nathaniel C. Comfort from Johns Hopkins University, claim that the change from state-led reproductive-genetic decision-making to individual choice has moderated the worst abuses of eugenics by transferring the decision-making from the state to the patient and their family.[137] Comfort suggests that "the eugenic impulse drives us to eliminate disease, live longer and healthier, with greater intelligence, and a better adjustment to the conditions of society; and the health benefits, the intellectual thrill and the profits of genetic bio-medicine are too great for us to do otherwise."[138] Others, such as bioethicist Stephen Wilkinson of Keele University and Honorary Research Fellow Eve Garrard at the University of Manchester, claim that some aspects of modern genetics can be classified as eugenics, but that this classification does not inherently make modern genetics immoral. In a co-authored publication by Keele University, they stated that "[e]ugenics doesn't seem always to be immoral, and so the fact that PGD, and other forms of selective reproduction, might sometimes technically be eugenic, isn't sufficient to show that they're wrong."[139]

In their 2000 book From Chance to Choice: Genetics and Justice, bioethicists Allen Buchanan, Dan Brock, Norman Daniels and Daniel Wikler argued that liberal societies have an obligation to encourage as wide an adoption of eugenic enhancement technologies as possible (so long as such policies do not infringe on individuals' reproductive rights or exert undue pressures on prospective parents to use these technologies) in order to maximize public health and minimize the inequalities that may result from both natural genetic endowments and unequal access to genetic enhancements.[140]

^Turda, Marius (2010). "Race, Science and Eugenics in the Twentieth Century". In Bashford, Alison; Levine, Philippa. The Oxford Handbook of the History of Eugenics. Oxford University Press. pp. 72–73. ISBN0-19-988829-9.

^"Consumption: Its Cause and Cure" An Address by Dr Halliday Sutherland on 4 September 1917, published by the Red Triangle Press.

^"Lancelot Hogben, who developed his critique of eugenics and distaste for racism in the period...he spent as Professor of Zoology at the University of Cape Town". Alison Bashford and Philippa Levine, The Oxford Handbook of the History of Eugenics. Oxford; Oxford University Press, 2010 ISBN 0199706530 (p.200)

^"Whatever their disagreement on the numbers, Haldane, Fisher, and most geneticists could support Jennings's warning: To encourage the expectation that the sterilization of defectives will "solve the problem of hereditary defects, close up the asylums for feebleminded and insane, do away with prisons, is only to subject society to deception". Daniel J. Kevles, In the Name of Eugenics. University of California Press, 1985. ISBN 0520057635 (p. 166).

^Congar, Yves M.-J. (1953). The Catholic Church and the race question(pdf). Paris, France: UNESCO. Retrieved 3 July 2015. 4. The State is not entitled to deprive an individual of his procreative power simply for material (eugenic) purposes. But it is entitled to isolate individuals who are sick and whose progeny would inevitably be seriously tainted.

^Lynn 2001. p. 18 "By the middle decades of the twentieth century, eugenics had become widely accepted throughout the whole of the economically developed world, with the exception of the Soviet Union."

^"Report of the IBC on Updating Its Reflection on the Human Genome and Human Rights"(PDF). International Bioethics Committee. 2 October 2015. p. 27. Retrieved 22 October 2015. The goal of enhancing individuals and the human species by engineering the genes related to some characteristics and traits is not to be confused with the barbarous projects of eugenics that planned the simple elimination of human beings considered as ‘imperfect’ on an ideological basis. However, it impinges upon the principle of respect for human dignity in several ways. It weakens the idea that the differences among human beings, regardless of the measure of their endowment, are exactly what the recognition of their equality presupposes and therefore protects. It introduces the risk of new forms of discrimination and stigmatization for those who cannot afford such enhancement or simply do not want to resort to it. The arguments that have been produced in favour of the so-called liberal eugenics do not trump the indication to apply the limit of medical reasons also in this case.

^Salgirli SG (July 2011). "Eugenics for the doctors: medicine and social control in 1930s Turkey". Journal of the History of Medicine and Allied Sciences. 66 (3): 281–312. doi:10.1093/jhmas/jrq040. PMID20562206.

^Lynn 2001. pp. 196–199. Quote: "There is, nevertheless, a good case for reviving the sterilization of the mentally retarded and criminals. It is indisputable on both empirical and theorethical ground that many of these people transmit their characteristics to their children by both genetic and environmental processes."

^Lynn 2001. pp. 199–201. First quote: "The rationale for this sentencing policy was that the judges considered these women unfit to rear children and that they should therefore be prevented from having more, at least for a few years." Second quote: "In these and similar cases many people will no doubt accept that the judges were right in deciding that the women were unfit mothers and likely to cause harm to any future children and that it would be desirable to prevent further pregnancies. It is preferable for these women to be put on probation conditional on temporary sterilization than to send them to prison, which in most cases would serve little useful purpose. These judges' decisions were not made ostensibly on eugenic grounds, but they furthered the eugenic objective of preventing these women from having children, at least for a limited period. The eugenic objective should be to support these judicial sentences and to promote their use more often, together with the stipulation of longer periods of contraception and, preferably, permanent sterilization"

^Lynn 2001. pp. 201–203. Quote: "A better alternative, from the point of view of reducing future criminal offending and the promotion of eugenics, would be for judges to offer convicted male criminals the alternatives of imprisonment or castration accompanied by probation."

^Lynn 2001. pp. 211–213. Richard Lynn argued that to have an effective licensing program, reversible sterilization methods should be used. Those who wish to have children would obtain the licence and have the sterilization reversed. Lynn stated that the proposals made by Francis Galton, Hugh LaFollette and John Westman would not be effective from the eugenics' viewpoint, since those without licences could still have children. The proposal by David Lykken would be only slightly effective.

^Lynn 2001. pp. 220–221. Quote: "While it can be confidently expected that elites would respond to financial incentives to have children and to penalties for childlessness by increasing their fertility, they might not do this to the extent that would be desired. Ideally a program of positive eugenics would increase the fertility of the elite to perhaps around four children per couple; and at the same time a complementary program of negative eugenics would reduce the fertility of those with low intelligence and psychopathic personality to zero.

^Lynn 2001. pp. 222–224. Quote: "The final strategy for the promotion of positive eugenics would consist of the acceptance of good-quality immigrants."

^ abMiller, Edward M. (1997). "Eugenics: Economics for the Long Run". Research in Biopolitics. 5: 391–416.

^Williams CC (2005). "In search of an Asperger". In Stoddart KP. Children, Youth and Adults with Asperger Syndrome: Integrating Multiple Perspectives. Jessica Kingsley. pp. 242–52. ISBN1-84310-319-2. The life prospects of people with AS would change if we shifted from viewing AS as a set of dysfunctions, to viewing it as a set of differences that have merit.

^Fischer, B. A. (2012). Maltreatment of people with serious mental illness in the early 20th century: A focus on Nazi Germany and eugenics in America. Journal of Nervous and Mental Disease, 200, 1096-1100. doi: 10.1097/NMD.0b013e318275d391

^Lynn 2001. The Ethical Principles of Classical Eugenics – Conclusions P. 241 Quote: "A number of the opponents of eugenics have resorted to the slippery slope argument, which states that although a number of eugenic measures are unobjectionable in themselves, they could lead to further measures that would be unethical. This argument is unpersuasive because all sorts of measures that are acceptable might, if taken to extremes, lead to other measures that are unacceptable."

^Shaw, p. 147. Quote: "What Rawls says is that “Over time a society is to take steps to preserve the general level of natural abilities and to prevent the diffusion of serious defects.” The key words here are “preserve” and “prevent”. Rawls clearly envisages only the use of negative eugenics as a preventative measure to ensure a good basic level of genetic health for future generations. To jump from this to “make the later generations as genetically talented as possible,” as Pence does, is a masterpiece of misinterpretation. This, then, is the sixth argument against positive eugenics: the Veil of Ignorance argument. Those behind the Veil in Rawls' Original Position would agree to permit negative, but not positive eugenics. This is a more complex variant of the Consent argument, as the Veil of Ignorance merely forces us to adopt a position of hypotethical consent to particular principles of justice."

^Harding, John R. (1991). "Beyond Abortion: Human Genetics and the New Eugenics". Pepperdine Law Review. 18 (3): 489–491. Retrieved 2016-06-02. Rawls arrives at the difference principle by considering how justice might be drawn from a hypothetical "original position.' A person in the original position operates behind a "veil of ignorance" that prevents her from knowing any information about herself such as social status, physical or mental capabilities, or even her belief system. Only from such a position of universal equality can principles of justice be drawn. In establishing how to distribute social primary goods, for example, "rights and liberties, powers and opportunities, income and wealth" and self-respect, Rawls determines that a person operating from the original position would develop two principles. First, liberties ascribed to each individual should be as extensive as possible without infringing upon the liberties of others. Second, social primary goods should be distributed to the greatest advantage of everyone and by mechanisms that allow equal opportunity to all. ... Genetic engineering should not be permitted merely for the enhancement of physical attractiveness because that would not benefit the least advantaged. Arguably, resources should be concentrated on genetic therapy to address disease and genetic defects. However, such a result is not required under Rawls' theory. Genetic enhancement of those already intellectually gifted, for example, might result in even greater benefit to the least advantaged as a result of the gifted individual's improved productivity. Moreover, Rawls asserts that using genetic engineering to prevent the most serious genetic defects is a matter of intergenerational justice. Such actions are necessary in terms of what the present generation owes to later generations.